Xerostomia, commonly known as “dry mouth,” is a condition in which the salivary glands do not produce sufficient quantities of saliva. Normally, mucous forms a continuous protective layer in the nose, mouth and throat. A patient suffering from xerostomia not only has decreased fluid in the mouth, but also an insufficient quantity of mucoproteins and mucopolysaccharides to hold fluid in contact with the cells and create a barrier to irritation and infection. This causes discomfort which can in some cases be quite severe. Without saliva, the mouth burns and the throat and tongue can undergo radical changes. Teeth can decay rapidly and the tongue can become smooth, cracked and vulnerable to infection.
Symptoms of mild xerostomia can be somewhat alleviated by the consumption of fluids, chewing gums, oral sprays, mouthwashes, hard candies and throat lozenges. Artificial saliva and salivary substitutes have also been proposed as palliative treatments for the symptoms of xerostomia, which preparations have physical and chemical properties that simulate those of natural (human) saliva. Examples of artificial salivas include compositions which contain ions that mimic those found in natural saliva, glycerin, as well as carboxymethylcellulose-based preparations to provide the proper level of viscosity. Fluoride ions are sometimes included to these preparations to prevent demineralization of tooth enamel. Nevertheless, these compositions have not found wide acceptance as many patients find that such preparations are irritating or distasteful and that their lubricating effect is of relatively short duration.